The disclosure relates to surface modification methods, surface modified articles, and to diagnostic applications using the articles. More specifically, the disclosure relates to cell culture surfaces for use in host vessels for biologicals, for example, culture vessels, labware, and in biosensors, such as a resonant waveguide grating (RWG) biosensors. The disclosure also relates to methods of making and using the cell culture surface modified biosensors for accomplishing label-free assays and like assays.